Pain relief is of prime importance to anyone treating patients undergoing surgery. Proper pain relief imparts significant physiological and psychological benefits to the patient. Not only does effective pain relief mean a smoother more pleasant post-operative course (e.g., mood, sleep, quality of life, etc.) with earlier discharge from medical/surgical/outpatient facilities, but it may also reduce the onset of chronic pain syndromes (e.g., fibromyalgia, myalgia, etc.).
Pain serves a biological function. It often signals the presence of damage or disease within the body and is often accompanied by inflammation (redness, swelling, and/or burning). In the case of post-operative pain, it may be a result of the surgery, or other treatments such as, for example, management of acute pain following burns or non-surgical trauma. The goal for post-operative pain management is to reduce or eliminate pain and discomfort with medication that cause minimum or no side effects.
The site of the surgery has a profound effect upon the degree of post-operative pain a patient may suffer. In general, operations on the thorax and upper abdomen are more painful than operations on the lower abdomen, which in turn are more painful than peripheral operations on the limbs. However, any operation involving a body cavity, large joint surfaces, the spine or deep tissues should be regarded as painful. In particular, operations on the thorax or upper abdomen may produce widespread changes in pulmonary function, an increase in abdominal muscle tone and an associated decrease in diaphragmatic function. The result will be an inability to cough and clear secretions, which may lead to lung collapse and pneumonia. Prolonged pain can reduce physical activity and lead to venous stasis and an increased risk of deep vein thrombosis and consequently pulmonary embolism. In addition, there can be widespread effects on gut and urinary tract motility, which may lead in turn to post-operative ileus, nausea, vomiting and urinary retention. These problems are unpleasant for the patient and may prolong hospital stay. Many patients that experience moderate to severe post-operative pain, post-traumatic pain and burning pains, often require pain control at least in the first 3 days after trauma or surgery.
One known class of pharmaceuticals to treat post-operative pain is opioids. This class of compounds is well-recognized as being among the most effective type of drugs for controlling post-operative pain. Unfortunately, because opioids are administered systemically, the associated side effects raise significant concerns, including disabling the patient, depressing the respiratory system, constipation, and psychoactive effects such as sedation and euphoria, thereby instituting a hurdle to recovery and regained mobility. Further, because of these side-effects, physicians typically limit the administration of opioids to within the first 24 hours post-surgery. Thus, it would be preferable to use non-narcotic drugs that deliver direct, localized pain control at a surgical site.
One pharmaceutical that is known to the medical profession is clonidine, which is widely recognized as an antihypertensive agent that acts as an agonist on the alpha-2-adrenergic receptor and as a neural receptor agonist. In general, clonidine, also referred to as 2,6-dichloro-N-2-imidazolidinyldenebenzenamine (C9H9Cl2N3) may be represented by the following chemical structure:

However, to date it has not been widely appreciated as an effective treatment for pain including post-operative pain and/or inflammation. Thus, there is a need to develop effective formulations of this compound for this application.